Pump or motor



c. l5, 1936., w. FERRIS ET AL f 2,064,299

PUMP OR MOTOR Filed Aug. 9, 1955 2 sheefsJsheet 1 Dec. i5, 193%. w. FERRIS ET AL 2,064,299

PUMP 0R MOTOR Filed Aug. 9, 1953 2 Sheets-Sheet 2 A wif-1W Patented ec. l5, i936 PU R MOTOR K. Douglas, Milwaukee, Qilgear Company, Milwaukee, Wis., a corporation of Wisconsin Application August 9, 1933, Serial No. 684,309

Walter Ferris and .llames Wis., assignors to The 21 Claims.

This invention relates to pumps and hydraulic motors of the type in which the cylinders are arranged in a cylinder barrel and revolve about a central shaft or pintle. upon which the cylinder barrel is journaled to rotate thereon and through which liquid flows to and from the cylinders, such as the pump described and claimed in Patent No. 1,930,163 which issued October 10, 1933 on the copending application of Walter Ferris, Serial No. 508,103., led January 12, 1931.

Pumps and motors of this character have as an inherent characteristic thereof a certain amount oi internal leakage or slipwhich Varies in accordance with variations in the clearance between the cylinder barrel and the pintle, variations in the uid pressure, and variations in the temperature of the motive fluid which is ordinarily a goo-d grade of lubricating oil and varies in viscosity in accordance with variations in its temperature. 4

It has heretofore been proposed to compensate for variations in the slip of a pump by varying pump displacement in response to variations in the temperature and thepressure of the oil, by

bypassing a part of the pump output and varying'this bypassed volume inversely to variations in the slip of the pump, and by varying the clearance between the cylinder barrel and the pintle. The'. latter method is employed in the hydraulic machine disclosed in the above application, but it is no-t readily applicable to a pump or motor in which the pintle is moved-in a direction transverse toits axis to vary pump displacement. Further, if this machine were employed as a motor and should stallunder a heavy load, the pressure in the end cylinders might urge the cylinder barrel along the pintle until the lubricating lm was squeezed from between the same and thereby cause the motor to have a low starting torque. Also, the cylinder barrel might seize upon the pintle.

The present invention has as an object to providea pump or motor in which the slip is maintained substantially constant under all operating conditions.

Another object is to provide a pump or motor the displacement of which may be varied by adjusting the pintlel and in which the clearance between the cylinder barrel and theA pintle is automatically varied in response to variations in the pressure and/or the viscosity of the motive liquid. A

Another objectwis to provide -a pump or motor with slip controlling meehanismwhich is positive and precise in operation.

4the pump or cylinder barrel 3 (on. 10s- 161) Other objects and advantages will be apparent from the description hereinafter given of a pump or motor in which the invention is embodied.

According to the invention in its general aspect and as ordinarily embodied in practice, the pump cr motor is provided with a tapered pintle having a cylinder barrel journaled thereon and with a fluid motor which urges the cylinder barrel toward the large end of the pintle and is energized by liquid which escapes from between the cylinder barrel. and the pintle.

According to the invention in another aspect, motor is provided with a tapered pintle, a cylinder barrel is journaled upon the pintle and urged toward the large end thereof by a fluid motor which is movable with the pintle.

The invention is exemplified by the hydraulic machine illustrated in the accompanying drawings in which the views are as follows:

Fig. 1 is a longitudinal vertical central section through the machine.

Fig. 2 is a sectional plan view taken on the line'2--2 of Fig. 1.

Fig. 3 is a detail view showing a valve in a different position from that occupied by itin Fig. 2.

The hydraulic machine shown in the drawings is identical to the machine shown in Patent No. 2,033,464 which issued March 10, 1936 on the copending application of Walter Ferris, Serial No. 669,'861, filed May 8, 1933. Hence, it has not been completely illustrated nor will it be described in detail herein.

The machine comprises, in general, a closed casing I, a pintle 2 arranged within the casing, a journaled upon the pintle and provided with a plurality 0f radial cylinders 4, a thrust member or driver 5 arranged around the cylinder barrel, a piston 6 arranged in each cylinder and coacting with the thrust member to transmit forces between it and the liquid in the cylinder, and a shaft 'l connected ,to the thrust member and extending through one end of the casing. 4

When the shaft 1 is driven from an outside source of power, the thrust member will reciprocate the pistons in the cylinders and rotate the..

. cylinder barrel upon the pintle and thereby cause the machine to `function as a pump and, when liquid under pressure is delivered to the Icylin- -ders, it will reciprocate the pistons in the cylpump or a motor but, for the purpose oi explanation, it will be described herein as a pump, and it is to be understood that the terms pump and motor as employed herein are substantially synonymous within the purview of the present invention.

When the'machine is employed as a pump, it is provided with a reservoir 8 which contains a supply of liquid and is shown arranged beneath the casing I and connected thereto t support the same.

The casing I is provided at its front end with a removable head 9 and at its rear end with a removable head I0.

The head 9 closes the front end of the casing I and carries an antifriction bearing II in which the shaft 'I is supported.

The head I0 closes the rear end of the casing and has formed therein two main fluid passages I2 and I3 which may be connected, respectively, to two pipes I4 and I5 of an external circuit by two pipe ttings I6 and II which are fastened to the rear head I0.

The passages I2 and I3 communicate, in the manner described in Patent No. 2,033,464, with fluid passages formed inV the pintle 2 longitudinally thereof, the passage I3 communicating with two upper pintle passages I8 and the passage I2 communicating with two lower pintle passages I 9.

The passages I8 and I9 communicate, respectively, at the front ends thereof .with two pintle ports 20 and 2I formed diametrically opposite each other in the front part of the pintle 2 which is tapered as shown in Fig. -1.

The cylinder barrel 3 is fitted upon `the tapered part of the pintle and provided with a cylinder port 22 for each of the cylinders 4. Each port 22 registers with the pintle ports 2U and 2| alternately as the cylinder barrel rotates to permit liquid to flow into its cylinder during one part of a revolution of the cylinder barrel and to enable the piston 6 in that cylinder to eject liquid therefrom through the other` pintle port during another part of a revolution of the cylinder barrel.

Each of the pistons B is tubular and providedv with a piston pin 23 which is connected at its outer end to a crosshead 24 and provided with a spherical head 25 which is ordinarily formed integral with the crosshead and engages a concave seat formed in the outer end of the piston.

The piston is closed at its outer end by the head 25 which is retained in rm engagement with its seat by a helical compression spring 26 arranged around the pin 23 between an annular shoulder formed in the piston near the outer end thereof and a collar xed on the inner end of the pin 23.

Each piston head 25 extends through an opening 21 which is formed in the inner wall of the driver midway between the ends of a tangential slot 28 which is formed in the driver 5 and in which the crosshead 24 is arranged to reciprocate.

Each crosshead 24 has its inner face in contact with the inner face of its slot 28 and its outer face in contact with a roller bearing 29 which is arranged in the slot and bears against a hardened bearing plate 30 fixed in the slot. The bearing plate 30 is -restrained from movement lengthwise of the slot by a screw 3l which also limits the movement of the roller bearing 29 along the slot.

Each piston is thus positively retainedv at a xed distance from the axis of-the driver and, when the axis of the driver is offset from the axis of the pintle and the driver is rotated, the

tegral, respectively, with the upper and-lower walls of the casing I and have arranged therebetween a pintle block 3E which may be formed integral with the pintle 2 but which is ordinarily made separate and rigidly secured thereon to form substantially a part thereof and to provide an oil-tight joint therewith.

The pintle block 36 is shaped to t between the opposing parallel faces of the guides 34 and 35 and to bear against the rear faces thereof against which it is normally pressed by hydrostatic pressure so that it and the pintle 2 are restrained by the guides from axial or vertical movement, but it may be moved along the guides to change the stroke of the pump.

The pintle block 36 is provided with two arcuate main uicl channels 31 and 38 which extend part way around the p-intle 2 and communicate, respectively, with the passages I9 and I8 through slots 3`Ia and 38a formed in the pintle 2 at the rear ends, respectively, of the passages I9 and I8.

The channels 31 and 38 communicate, respectively, at the other ends thereof with the passages I2 and I3 through sliding joints 39 and 4I) so that the liquid flowing through the pintle passages at one side of the pintle axis ows through the sliding joints at the other side of the pintle axis, thereby hydrostatically balancing the pintle block as fully explained in Patent No. 2,033,464.

If the machine is to be employed as a pump, it is ordinarily provided with an auxiliary gear pump the output of which may be employed for control and other'auxiliary purposes, to compensate for leakage losses, to enable the variable pump to operate differential motors, and/or to supercharge the variable pump.

The gear pump is of ordinary construction and consists of a driving gear 4I, which'is xed upon the shaft 'I to rotate therewith, and a driven gear 42 which meshes with the gear 4I and is carried by a stub shaft 43 supported in the front head 9. The gears 4I and 42 are fitted in a pump chamber 44 which is formed in the front head 9 in communication with suitable intake and discharge channels also formed therein,

The machine thus far described forms, of itself, no part of the present invention as itis fully illustrated and described and the patentable characteristics thereof claimed in Patent No. 2,033,464.

When the pump is in operation, liquid 'from the pintle discharge port seeps between the cylinder `barrel and the pintle and spreads over that area of the pintle which is covered by the cylinder barrel. This liquid forms a lubricating film between the cylinder barrel and the pintle'and then a part of this liquid escapes into the intake port and another part thereof escap'es from the ends of the cylinder barrel.

The total volume 4of liquid thus escaping from A from between the two parts of the sliding joints 39 and 40 is generally designated as the real slip of the pump, and this slip variesin accordance with the variations in the clearance between the cylinder barrel and the pintle, variations in pump pressure, and variations in the viscosity of the liquid.'

The pump also has what is known as apparent slip which is a variation in its output due to a variation in pump pressure and is caused by the compressibility of the motive liquid and the deflectionof the pump parts. The present invention compensates for the entire pump slip, that is, both the real and the apparent slip.

The lubricating film between the cylinder barrel and the pintle is under a pressure which, in a pump having a balanced pintle, is substantially equal to pump pressure at the edges of the pressure port and diminishes as the distance from this port increases, the pressurer on the 'opposite side of the pintle being lower and the pressure at the ends of the cylinder barrel being substantially zero.

The pressure in the lubricating film acts upon the tapered inner surface ofthe cylinder barrel and the tapered outer surface of the pintle and urges the cylinder .barrel toward the small end of the pintle with a force which is substantially proportional to pump pressure, thereby tending toincrease the clearance between thecylinder barrel and the pintle with a resultant increase in the slip of the pump. v

In order to overcome this tendency and to maintain the slip of the pump substantially constant under all normal operating conditions, the present invention provides mechanism for urging the cylinder barrel toward the large end of the pintle with a force which varies in accordance with Variations in pump pressure.

This mechanism includes a piston which is carried by the pintle and consists primarily of a circular plate or flange 45, which is fastened'to the end of the pintle, and a oating ring 46 which bears against the rear face of the plate 45 and ordinarily has an expansible piston ring 41 inserted in its outer annular face.

This two-part piston is enclosed Within a cylinder 48 which is fastened lto or formed integral with the cylinder barrel, extends beyond the end of the pintle, and is closed at its outer end by a cap plate 49 having one or more drainage holes 53 formed therein to permit the escape of any liquid which may seep past the piston ring 41.

If the floating ring 46 and the cylinder 48 had the same coefficient of expansion and if the several parts were made with micrometric accuracy, the piston ring 41 would not be necessary.

The oating ring l46 is rotated by and with the cylinder barrel through one or'more driving pins 5|, and it is retained in contact with the rear face of the plate 45 by a number of vequally spaced compression springs 52 which are arranged in suitable recesses formed in the cylinder barrel.

The piston ring 41 rotates in unison with the floating ring 46 and the cylinder 48 and, consequently, there is no appreciable wear of either the piston-ring or the inner wall of the cylinder 48.

The floating ring 46 thus rotates in Contact with the rear face of the plate 45, and the contact faces thereof are lubricated by liquid which enters through a number of lubricating grooves 53 which are formed in the plate 45.

Of the liquidA which constitutes the internal leakage or slip of the pump, that part which escapes from between the cylinder barrel and the pintle at the front end thereof enters the cylinder 48 and creates therein' a pressure which acts upon the inner end of the cylinder 48 and upon the rear face of th piston 45-46. Since the piston 45--46 is restrained from axial' movement by being fixed to thespintle, this pressure urges the cylinder barrel toward the` large end of the pintle to reduce 'the clearance between the cylinder bar-` rel and the pintle and thereby reduce the slip ofA the pump. l0

Liquid may escape from the cylinder 48 through a radial passageway 54vwh`ch is formedY in the. rear face of the plate 45, 'an axialpassageway 55` which is formed in the pintle 2 and communicates at its front end with the passageway 54, and a 15 radial passage 56, which is formed in the pintle 2 and in the pintle block 36 and communicates at its innerend with the passage 55.

The escape of liquid from the cylinder 48 is retarded by directing the liquid through a restricted passage or other choke or resistance in order to control the pressure in the cylinder 48. As shown, a choke 51 and a pressure responsive valve 58 are arranged in the pintle block 36 and connected to the passage 56 in parallel with eachother.

The choke 51 consists of one or more disks 59' (9 being shown) which are closely fitted in a bore 66 extending inward from the rear end of the pintle block 36 and communicating with the pas- :age 56.

Each disk 59 is provided with a small orifice 6|, and the several disks are retained in position Within the bore 66 by spacer rings 62 which are heldin .position within the bore 6i) by a ring or hollow plug 53 threaded in the rear end thereof.

If a single disk 59 were employed, the orifice 6| therein would necessarily be so small that it might readily become clogged by foreign matter carried by the motive liqiud. Hence, in practice, each crice is made larger and a number of disks are employed.

The several disks and spacer rings form a series of low pressure chambers and, since the rate of flow of liquid through an orifice depends upon the drop in pressure across-the erin-ce, this series of pressure chambers and orifices provide such resistance that the rate of flow of liquid therethrough is very low even when va relatively high pressure prevails in the passage 56.

- The pressure responsive valve 58 is provided with a hollow piston 64- which is closely fitted for reciprocation within a bore 6 5 formed in the pintle block 36 and having a ring or hollow plug 66 threaded intothe rear end thereof.

The piston 64 is provided at its inner end with 55 a valve stem 61 having a valve or head 68 fixed upon the inner end-thereof and normally arranged in a chamber 68 formed in the pintle block 36. i

The chamber 69 is connected at its front en 60 to the passage 56 by'a passage 10and communicates at its rear end with the bore through a smaller bore 1l the diameter of which is substantially the same as the diameter of the valve 68 and into which a predetermined high pressure 65 in the passage 56 will urge the valve 68 to close communication between the passage -56 and the bore 65.l I The piston 64 is normally retained in engagement with the front end of the bore 65 by a helical compression spring 12 which is arranged therein between the front or head end thereof and the plug 66.

The front or head end of the piston 64 is provided with a chamber 13 which communicates at 75 its front end with the bores 65 and 1I through small ducts 14 arranged around the stem 61, and which is partially closed at its rear end by a replaceable plug 15 having a small orice 16 formed therein.

When the piston 64 is in the position shown in Fig. 2, liquid from the cylinder 48 may ow through the Valve 58 via the chamber 69, the bores 1| and 65, the ducts 14, the chamber 13 and the orifice 16 and, if the rate of iiow therethrough is, incorrect, it may be varied by replacing the plug 15 with a similar plug having an orice 16 of different cross-sectional area.

The orifice 16 limits the rate at which liquid may flow through the valve 58 and, when the rate of flow exceeds the capacity of the orifice 16, there will be created in the liquid a pressure which varies in accordance with the variations in the rate of liquid flow.

This pressure acts upon the front ends of the piston 64 and the valve 68 and, when the rate of flow increases to the point where the force exerted thereon by the liquid exceeds the resistance of the spring 12, the piston 64 and the valve 68 will be urged rearward until the valve 68 reduces the ow to the rate at which liquid can pass through the orifice 16, thereby reducing the pressure in the bores 65 and 1| and leaving only the front end of the valve 68 exposed to the pressure in the passage 10. If lthis pressure is high enough, the force exerted by the liquid upon the valve 68 will urge it into the bore 65 so that any liquid which escapes from the cylinder 48 must pass through the choke 51.

When the pump is operated at pressures within a given pressure range, the resistance of the spring 12 in the valve 58 is substantially balanced by the pressure on the piston 64 and the valve 68 so that the valve 68 ordinarily floats between a fully open and a fully closed position.

'I'he rate of flow through the valve 58 thus decreases as the pressure increases While the rate of flow through the choke 51 increases as the pressure increases.

The choke 51 and the valve 58 provide a combination of resistances which may be so proportioned and adjusted as to maintain substantially constant the total slip consisting of both the real and the apparent slip.

When the pump is idle, there is always suflicient clearance between the cylinder barrel and the pintle to permit the lubricating film therebetween to be replenished or established during the first few revolutions of the cylinder barrel.

This clearance is assured by providing a helical compression spring 11 -between the plate 45 which is xed to the pintle and the plate 49 which isxed to the cylinder barrel, a ball bearing 18 being arranged between the outer end of the spring and the plate 49 to prevent the spring from being rotated by the cylinder barrel.

The spring 11 also prevents the cylinder barrel from shrinking upon the pintle in case the cylinder barrel should have a higher coefficient of expansion than the pintle `and the pump be stopped immediately after operating under high temperatures and pressures.

If the spring 11 should move the cylinder barrel too far forward, the pump when started would simply bypass liquid from one pintle port to the other. It is therefore. essential that the forward movement of the cylinder barrel be limited, and this is ordinarily accomplished by limiting the distance between the fioating ring 46 and the' in due to the resistance of the choke 51 and the valve 58 to the escape of liquid therefrom.

This low pressure urges the cylinder barrel toward the large end of the cylinder to reduce the clearance therebetween and thereby reduce the rate at which liquid escapes from between the cylinder barrel and the pintle but, at the same time, the liquid between the cylinder barrel and the pintle is acting upon the tapered surfaces thereof and urging the cylinder barrel toward the small end of the pintle with a force which varies in accordance with variations in pump pressure, thereby tending to increase the slip of the pump.

'Ihe rate at which liquid will ow through a restricted passage varies in accordance with variations in either or both the pressure and the viscosity of the liquid.

Therefore, as the pump pressure or the temperature of the motive liquid increases, liquid will flow between the cylinderand the pintle and into the cylinder 48 at a faster rate and thereby tend to escape from the cylinder 48 through the passages 54, 55 and 56 at a faster rate.

However, the escape of liquid from the cylinder 48 is restricted by the choke 51 and the valve 58 so that the pressure in the cylinder 48 increases and urges the cylinder barrel rearward against the resistance of the spring 11 and against the forces exerted upon the tapered bore of the cylinder barrel by the lubricating film and, as the area of the cylinder 48 is such that a relatively low pressure therein exerts a greater rearward force upon the cylinder barrel than the forward force exerted thereon by the lubricating film, the cylinder barrel is moved rearward and the clearance between the cylinder barrel and the pintle is reduced.

The choke 51 and the valve 58 are so proportioned and adjusted that the pump will have at a given low pressure a total slip which is at least as great as its total slip would be at a pressure higher than any pressure which the pump will create under normal operating conditions.

Then, as the pump pressure increases with a resultant increase in pressure in the cylinder 48 and in the passage 56, the flow of liquid through the choke 51 will increase and the ow of liquid through the valve 58 will decrease.

If the valve 58 were adjusted to decrease the flow of liquid therethrough at the same rate that the fiow through the choke 51 increases,

the flow of liquid from between the cylinder bar-V rel and the pintle into the cylinder 48 would be maintained constant but, since the total slip consists also of other factors such as the liquid which escapes past the pistons and from the rear end of the cylinder barrel, compressibility of the liquid and deflection of pump parts, the valve 58 is adjusted to decrease the ow therethrough faster than the flow through the choke 51 increases to thereby increase the pressure in the cylinder '48 with the result that the cylinder barrel is urged rearward and the rate at which liquid can flow into the cylinder 48 is decreased in proportion to the increase in the other slip factors, thereby maintaining the net output of the pump 'substantially constant throughout the entire range of operating temperatures and pressures.

Also, the pump may be adjusted to compensate for variations in leakage in a hydraulic circuit fed by it, providing that the leakage is not excessive and the variations therein are due to variations in pump pressure, thereby obtaining a substantially constant speed in any motor connected into that circuit.

If the pump is to compensate for leakage in a circuit, it is adjusted to have at a low pressure an initial slip which is at least as great as the combined pump slip and circuit leakage at a pressure at least as high as the greatest pressure created in the circuit by the pump under normal operating conditions, and then the choke 57 and the valve 58 are adjusted to lcompensate for variations in slip, as previously explained.

If the pump is to be employed as a motor, it is necessary to adjust choke 51 and valve 5% to obtain a constant motor speed throughout the range of operating pressures since the factors which constitute the slip of a motor diier somewhat from the factors which constitute the slip of a pump.

The invention herein set forth is susceptible of various modifications without departing from the scope thereof as hereinafter claimed.

I'he invention is hereby claimed as follows:

l. In a pump or motor, the combination of a tapered pintle, a cylinder barrel journaled upon said pintle, a fluid motor for urging said cylinder barrel toward the large end of said pintle and means for energizing said motor by directing thereto liquid which escapes from between said cylinder barrel 'and said pintle.

2. In a pump or motor, the combination of a tapered pintle adapted to be moved to vary the displacement of said pump or motor, a cylinder barrel journaled upon said pintle, a iiuid motor for urging said cylinder barrel toward the large end of said pintle and movable with said pintle, and means for energizing said motor by directing thereto liquid which escapes from between said cylinder barrel and said pintle.

3. In apump or motor, the combination of a tapered pintle, a cylinder barrel journaled upon and carried by said pintle, a fluid motor for urging said cylinder barrel toward thelarge end of said pintle carried by said pintle, and means for energizing said motor by directing thereto liquid which escapes from between said cylinder barrel and said pintle.

4. In a pump or motor, the combination of a tapered pintle, a cylinder barrel journaled upon said pintle, a iiuid motor for urging said cylinder barrel toward the large end of said pintle, means for energizing said motor by directing thereto liquid which escapes from between said cylinder barrel and said pintle, and means for controlling'the escape of liquid from said motor.

5. In a pump or motor, the combination of a tapered pintle,l a cylinder barrel journaled upon said pintle, a uid motor for urging said cylinder barrel toward the large end of said pintle, means for directing liquid leaking from between said cylinder barrel and said pintle to said motor to energize the same, and means responsive to variations in the pressure in varying the rate of escape of liquid therefrom.

6. A pump or motor, comprising a casing, a tapered pintle provided with intake and discharge ports and passages arranged within said casing and restrained from axial movement relative thereto, a cylinder barrel iitted upon and carsaid motor for ried by said pintle kto rotate thereon and provided with cylinders which communicate with said pintle ports alternately as said cylinder barrel rotates, pistons arranged in said cylinders, means for rotating said cylinder barrel and reciprocating said pistons, and a piston and a cylinder carried by said pintle and operated by liquid from said cylinders to urge said cylinder barrel toward the large end of said pintle and thereby control the escape of liquid from between said cylinder barrel and said pintle.

7. A pump or motor, comprising a casing, a tapered pintle provided with intake and discharge ports and passages arranged within said casing and restrained from axial movement relative thereto, a cylinder barrel fitted upon and `carried by said pintle to rotate thereon and provided with cylinders which communicate with` said pintle ports alternately as said cylinder barrel rotates, pistons arranged in said cylinders, means for rotating said cylinder barrel and reciprocating said pistons, a piston and a cylinder carried by said pintle and operated by liquid from said cylinders to urge said cylinder barrel toward the large end of said pintle and thereby control the escape of liquid from between said cylinder barrel and 'said pintle, means for permitting `escape of liquid from said last named cylinderand means for controlling the rate of said escape.

8. A pump or motor, comprising a casing, a tapered pintle provided with intake and discharge ports and passages arranged Within said casing and movable transversely to vary pump displacement but restrained from axial movement relative to said casing, a cylinder barrel fitted upon said pintle to rotate thereon and provided with cylinders which communicate with said pintle ports alternately as said cylinder barlrel rotates, pistons arranged in said cylinders,

means for rotating said cylinder barrel and reciprocating said pistons, and a piston and a cylinder movable with said pintle and operated by liquid from said cylinders to urge said cylinder barrel toward the large end of said pintle and thereby control the escape of liquid from between said cylinder barrel and said pintle.

9. A pump or motor, comprising a casing, a tapered pintle provided with intake and discharge ports and passages arranged within said casing and movable transversely to vary pump displacement but restrained from axial movement relative to said casing, a cylinder barrel fitted upon said pintle to rotate thereon and provided with cylinders which communicate with said pintle ports alternately as said cylinder barrel rotates, pistons arranged in said cylinders, means for rotating said cylinder barrel and reciprocating said pistons, a piston and a cylinder movable with said pintle and operated by liquid from said cylinders to urge said cylinder barrel toward the large end of said pintle and thereby control the escape of liquid from between said cylinder barrel and said pintle, and means for controlling the rate at which liquid may escape from said last named cylinder.

l0. A pump or motor, comprising a casing, a tapered pintle provided with intake and discharge ports and passages arranged within said casing and restrained from axial movement relative thereto, a cylinder barrel fitted upon and carried A rotates, pistons arranged inl said cylinders, l

means'including a driveshaft for rotating said cylinder barrel and reciprocating said pistons, and a piston and a cylinder arranged between said driveshaft and said pintle and operated by liquid from said cylinders to urge said cylinder barrel toward the large end of said pintle and thereby control the escape of liquid from between said cylinder barrel and said pintle.

11. The combination, with a pump or motor having a tapered pintle and a cylinder barrel journaled upon said pintle to rotate thereon, of a piston arranged upon one end of said pintle, and a cylinder fitted upon said piston and arranged upon said cylinder barrel to receive leakage liquid from between said cylinder barrel and said pintle to enable said liquid to create pressure in said cylinder and urge said cylinder barrel toward the large end of said pintle and thereby tend to reduce the clearance between said cylinder barrel and said pintle.

12. The combination, with a pump or motor having a tapered pintle and a cylinder barrel journaled upon said pintle to rotate thereon, of a piston arranged upon one end of said pintle, a cylinder iitted upon said piston and arranged upon said cylinder barrel to receive leakage liquid from between said cylinder barrel and said pintle to enable said liquid to create pressure in said cylinder and urge` said cylinder barrel toward the large end of said pintle and thereby tend to reduce the clearance between said cylinder barrel and said pintle, and means for controlling the escape of liquid from said cylinder to thereby control the pressure therein.

13. The combination, with a pump or motor having a tapered pintle and a cylinder barrel journaled upon said pintle to rotate thereon, of a piston arranged upon one end of said pintle, a cylinder tted upon said piston and arranged upon said cylinder barrel to receive leakage liquid from between said cylinder barrel and said pintle to enable said liquid to create pressure in said cylinder and urge said cylinder barrel toward the large end of said pintle and thereby tend to reduce the clearance between said cylinder barrel and said pintle, and means urging said cylinder barrel toward the small end of said pintle and thereby tending to increase the clearance between said cylinder barrel and said pintle.

14. The combination, with a pump or motor having a tapered pintle and a cylinder barrel journaled upon said pintle to rotate thereon, of a piston arranged upon one end of said pintle, a cylinder tted upon said piston and arranged upon said cylinder barrel to receive leakage liquid from between said cylinder barrel and said pintle to enable said liquid to create pressure in said cylinder and urge said cylinder barrel toward the large end of said pintle and thereby tend to reduce the clearance between said cylinder barrel and said pintle, means for controlling the escape of liquid from. said cylinder to thereby control the pressure therein, and means urging said cylinder barrel toward the small end of said pintle and thereby tending to increase the clearance between said cylinder barrel and said pintle.

15. 'I'he combination, with a pump or motor having a tapered pintle and a cylinder barrel journaled upon said pintle to rotate thereon, of a piston arranged upon one end of saidpintle, a cylinder fitted upon said piston and arranged upon said cylinder barrel to receive leakage liquid from between said cylinder barrel and said pintle to enable said liquid to create pressure in said'cylinder and urge said cylinder barrel toward the large end of said pintle and thereby tend to reduce the clearance between said Vcylinder barrel and said pintle, and means responsive to the pressure in said cylinder for controlling the escape of liquid therefrom to thereby control the pressurein said cylinder and thereby control the escape of liquid from between said cylinder barrel and said pintle.

16. The combination, with a pump or motor having a tapered pintle and a cylinder barrel journaled upon said pintle to rotate thereon, of a piston arranged upon one end of said pintle, a cylinder fitted upon said piston and arranged upon said cylinder barrel to receive. leakage liquid from between said cylinder barrel and said pintle to enable said liquid to create pressure in said cylinder and urge said cylinder barrel toward the large end of said pintle and thereby tend to reducel the clearance between said cylinder barrel and said pintle, and means for controlling the escape of liquid from said cylinder including an orice choke and a pressure responsive valve connected in parallel with each other.

17. In a pump or motor having a tapered pintle and a cylinder barrel journaled upon said pintle to rotate thereon, the combination of a piston connected to said pintle and restrained from axial movement thereby, and a cylinder fitted upon said piston and arranged upon said cylinder barrel to receive leakage liquid from between said cylinder barrel and said pintle to enable said liquid to create pressure in said cylinder and urge said cylinder barrel toward the large end of said pintle and thereby tend to reduce the clearance between said cylinder barrel and said pintle, said piston having a part thereof arranged to rotate with said cylinder.

18. In a pump or motor having a tapered pintle and a cylinder barrel journaled upon said pintle to rotate thereon, the combination of a cylinder arranged upon said cylinder barrel to receive liquid leaking from between said cylinder barrel and said pintle, a piston tted in said cylinder and having a part thereof rotatable with said cylinder and another part thereof connected to said pintle to be restrained from relative axial movement thereby, and means for resisting the escape of liquid from said cylinder to enable the liquid therein to urge said cylinder barrel toward the large end of said pintle and 'thereby tend to reduce the clearance between said vcylinder barrel and said pintle.

19. In a pump or motor having a tapered pintle and a cylinder barrel journaled upon said pintle to rotate thereon, the combination of a cylinder arranged upon said cylinder barrel to receive liquid leaking from between said cylinder barrel and said pintle, a piston tted in said cylinder and having' a part thereof rotatable with said cylinder and another part thereof connected to said pintle to be restrained from relative axial movement thereby, packing means arranged between said rotatable piston part and the wall of said cylinder and rotatable therewith, and means for resisting the escape of liquid from said cylinder to enable the liquid therein to urge said cylinder barrel toward the large end of said pintle andthereby tend to reduce the clearance between said cylinder barrel and said pintle.

20. In a pump having a tapered pintle and a cylinder barrel tted upon said pintle to rotate thereon, the combination of a flange carried by said pintle upon the end thereof, a iloating ring abutting said flange and making a tight running joint therewith and connected to said cylinder barrel to rotate therewith in contact with said flange, and a cylinder connected at its rear end to said cylinder barrel to receive liquid leaking from between said cylinder barrel and said pintle and fitted upon said floating ring to enable it to resist the escape of liquid through the iront end of said cylinder to thereby enable liquid in said cylinder to urge said cylinder barrel toward th large end of said pintle.

k21. In a pump having a tapered pintle and a cylinder barrel fitted upon said pintle to rotate thereon, the combination of a flange carried by said pintle upon the end thereof, a oating ring abutting said flange and making a tight running joint therewith and connected to said cylinder barrel to rotate therewith in contact with said ange, a cylinder arranged upon said cylinder barrel to enclose said ring and said flange and to receive liquid leaking from between said cylinder barrel and said pintle, a piston ring carried by'said oating ring in contact with the wall of said cylinder and forming with said floating ring. and said flange a piston for said cylinder to enable liquid entering said cylinder to urge said cylinder barrel toward the large end of said pintle, means for controlling the escape of liquid from said cylinder, and means urging said cylinder barrel toward the small end of said pintle.

WALTER FERRIS.

JAMES K. DOUGLAS. 

